Editor’s note (4/2/2017): This week marks the 100-year anniversary of the U.S. entry into the First World War. Scientific American, founded in 1845, spent the war years covering the monumental innovations that changed the course of history, from the first tanks and aerial combat to the first widespread attacks with chemical weapons. To mark the centennial, we are republishing the article below and many others. For full access to our archival coverage of the Great War sign up for an All Access subscription today.

Reported in Scientific American, This Week in World War I: July 31, 1915 

The world’s first full-scale attack by poison gas took place on April 22, 1915, near the town of Ypres in Belgium. It was a stunning success for the Germans who deployed it, and a catastrophe for the French territorial troops who were unfortunate enough to be on the receiving end of this new form of chemical warfare.

When an armed force must suddenly fight against an effective new weapon, the people tasked with winning wars scramble to find some kind of workable protection for their troops. The Allies did not know the exact nature of the gas but were pretty sure it was chlorine. The first attempts at gas defense came from industrial safety equipment used in factories that had to deal with chlorine fumes: flannel pads soaked in various liquids to cover the mouth (goggles were added later).

But more was needed. The suggestion in this Scientific American article, and the illustration it contained (above), was an earnest and perhaps desperate search for a technological fix for poison gas. (The soldiers manning the trench are shown wearing the flannel pads then in use.)

“[One inventor] proposes the use, in the trenches near enough to the enemy to be in danger from such gases, of rotary fan-blowers worked by hand placed at about every three or four yards. The fan-blowers should be connected with pipes going through the base of the earthwork in front of the trench. If the number of blowers were equal to the number of gas cylinders used by the enemy, the blowers when vigorously worked would deliver a far greater volume of air than the volume of the poisonous gas, so that the gas would become much diluted, and with good respirators would be harmless to our men. We believe that experiments are being conducted at the front with the object of devising means to render the poisonous gases innocuous by spraying with water and in other ways.”

I do not believe the scheme depicted was ever tried. If it was, I pity the poor infantryman on the front lines desperately cranking these fans and cursing the powers-that-be. But there are sound reasons why the idea was considered in the first place. The earliest method of launching a  chlorine gas attack was to lug large cylinders full of chemical to the front line, wait for just the right wind blowing gently (not too fast, not too slow) in exactly the right direction (and not when it’s raining or drizzling, or too hot or too cold), and then open the cylinders. In a light breeze, if the targeted soldiers had been able to fan the gas around, it is faintly possible that the gas might have been diluted enough to reduce casualties: “A slight counter air current ought to suffice, therefore, to deflect the direction of the gas cloud as it slowly drifts over the ground between the two lines of trenches,”

In any event, the better response was to develop a good gas mask for the individual soldier (or civilian), manufacture large numbers of them, and distribute them as fast as possible. Given how effective gas could be, both sides developed increasingly sophisticated methods of delivering the chemicals at much longer ranges and in different conditions: by artillery shells, grenades or bombs. And as fast as gas masks were developed, new gases were introduced to the battlefield that quickly rendered older protection obsolete.


Our full archive of the war, called Scientific American Chronicles: World War I, has many articles from 1914–1918 on chemical warfare and defense against it. It is available for purchase at www.scientificamerican.com/products/world-war-i/